title: Proteins in action: femtosecond to millisecond structural dynamics of a photoactive flavoprotein.
abstract: Living systems are fundamentally dependent on the ability of proteins to respond to external stimuli. The mechanism, the underlying structural dynamics, and the time scales for regulation of this response are central questions in biochemistry. Here we probe the structural dynamics of the BLUF domain found in several photoactive flavoproteins, which is responsible for light activated functions as diverse as phototaxis and gene regulation. Measurements have been made over 10 decades of time (from 100 fs to 1 ms) using transient vibrational spectroscopy. Chromophore (flavin ring) localized dynamics occur on the pico- to nanosecond time scale, while subsequent protein structural reorganization is observed over microseconds. Multiple time scales are observed for the dynamics associated with different vibrations of the protein, suggesting an underlying hierarchical relaxation pathway. Structural evolution in residues directly H-bonded to the chromophore takes place more slowly than changes in more remote residues. However, a point mutation which suppresses biological function is shown to 'short circuit' this structural relaxation pathway, suppressing the changes which occur further away from the chromophore while accelerating dynamics close to it.
authors.affiliation: Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States.
authors.forename: Richard
authors.initials: R
authors.lastname: Brust
authors.forename: Andras
authors.initials: A
authors.lastname: Lukacs
authors.forename: Allison
authors.initials: A
authors.lastname: Haigney
authors.forename: Kiri
authors.initials: K
authors.lastname: Addison
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Gil
authors.forename: Michael
authors.initials: M
authors.lastname: Towrie
authors.forename: Ian P
authors.initials: IP
authors.lastname: Clark
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Greetham
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Tonge
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Meech
mesh_terms: D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry; D005420:Flavoproteins / Q000737:chemistry* / Q000235:genetics; D006860:Hydrogen Bonding; D007700:Kinetics; D008958:Models, Molecular; D010777:Photochemistry; D017354:Point Mutation; D011487:Protein Conformation; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared; D014732:Vibration
chemical_list: D005420:Flavoproteins; D005182:Flavin-Adenine Dinucleotide